<div class="input-group flex-nowrap">
  <div class="input-group-prepend">
    <span class="input-group-text" id="addon-wrapping">序号</span>
  </div>
  <input type="text" class="form-control" placeholder="numeber" aria-label="numeber" aria-describedby="addon-wrapping">
</div>
<div class="input-group flex-nowrap">
  <div class="input-group-prepend">
    <span class="input-group-text" id="addon-wrapping">用户名</span>
  </div>
  <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="addon-wrapping">
</div>
<div class="input-group flex-nowrap">
  <div class="input-group-prepend">
    <span class="input-group-text" id="addon-wrapping">密码</span>
  </div>
  <input type="text" class="form-control" placeholder="password" aria-label="password" aria-describedby="addon-wrapping">
</div>
<table>
  <thead>
      <th>用户序号</th>
      <th>用户名</th>
      <th>密码</th>
  </thead>
  <tbody>
      <tr>
          <td>1</td>
          <td>gyc1234</td>
          <td>123456</td>
      </tr>
      <tr>
          <td>2</td>
          <td>aaa123</td>
          <td>456789</td>
      </tr>
      <tr>
          <td>3</td>
          <td>gongyc123</td>
          <td>2345678</td>
      </tr>
  </tbody>
</table>
<button type="button" class="btn btn-secondary">查询</button>
<button type="button" class="btn btn-primary">添加</button>
<button type="button" class="btn btn-success">修改</button>
<button type="button" class="btn btn-danger">删除</button>